| Animal Research: |
| Front Cell Dev Biol . 2020 Nov 17;8:576988. | | Bixin Protects Against Kidney Interstitial Fibrosis Through Promoting STAT6 Degradation[Pubmed: 33313043] | | Bixin, a natural carotenoid extracted from the seeds of Bixa orellana, has antioxidant and anti-inflammation effects. However, the pharmacological effects and underlying mechanisms of Bixin in kidney interstitial fibrosis remain unknown. Partial epithelial-to-mesenchymal transition (EMT) of tubular cells has been linked to renal interstitial fibrosis. Here, we found that in the unilateral ureteral obstruction model, Bixin administration could ameliorate kidney interstitial fibrosis. The expression of signal transducer and activator of transcription 6 (STAT6) was dramatically increased in renal tubular cells. Bixin treatment inhibited STAT6 induction. The activation of STAT6 signaling was essential for transforming growth factor β1, fibrotic markers, and EMT-related protein expression in HK2 cells, which was confirmed by using the Stat6 mice. Ubiquitination, but not the acetylation level of STAT6, was induced by Bixin treatment and promoted the suppression of phosphorylation and stability of STAT6. P62-dependent autophagy might be involved in this process. The study demonstrated that Bixin can be exploited therapeutically to alleviate renal interstitial fibrosis by targeting STAT6 signaling deactivation. -/- | | Front Immunol . 2020 Dec 9;11:593368. | | Bixin Attenuates Experimental Autoimmune Encephalomyelitis by Suppressing TXNIP/NLRP3 Inflammasome Activity and Activating NRF2 Signaling[Pubmed: 33362775] | | Multiple sclerosis (MS), an autoimmune and degenerative disease, is characterized by demyelination and chronic neuroinflammation. Bixin is a carotenoid isolated from the seeds of Bixa orellana that exhibits various potent pharmacological activities, including antioxidant, anti-inflammatory, and anti-tumor properties. However, the effects of Bixin on MS have not yet been examined. To evaluate the effects and underlying molecular mechanisms of Bixin on MS, experimental autoimmune encephalomyelitis (EAE) was established in C57BL/6 mice, which were treated via intragastric administration of Bixin solutions. To evaluate the molecular mechanisms of Bixin, quantitative reverse-transcription PCR, western blot, immunohistochemistry, flow cytometry, and enzyme-linked immunosorbent assay analyses were performed. We found that Bixin significantly improved the symptoms and pathology in EAE mice, reduced the release of inflammatory cytokines TNF-α, IL-6, IL-8, IL-17, and IFN-γ, and increased the expression of the anti-inflammatory cytokine IL-10. And Bixin reduced the proportion of Th1 and Th17 cells in the spleen and CNS, and suppressed microglia aggregation, and TXNIP/NLRP3 inflammasome activity by scavenging excessive reactive oxygen species (ROS) in EAE mice. Furthermore, Bixin inhibited inflammation and oxidative stress via activating nuclear factor erythroid 2-related factor 2 (NRF2), and its downstream genes in EAE mice, meanwhile, these effects were suppressed upon treatment with an NRF2 inhibitor, ML385. Bixin prevented neuroinflammation and demyelination in EAE mice primarily by scavenging ROS through activation of the NRF2 signaling pathway. Taken together, our results indicate that Bixin is a promising therapeutic candidate for treatment of MS. | | Int Immunopharmacol . 2021 Jan;90:107117. | | Bixin attenuates carbon tetrachloride induced oxidative stress, inflammation and fibrosis in kidney by regulating the Nrf2/TLR4/MyD88 and PPAR-γ/TGF-β1/Smad3 pathway[Pubmed: 33162346] | | Bixin, an natural carotenoid extracted from the seeds of the Bixa orellana has been shown to possess numerous important pharmacological activities. The present study was aimed to investigate the mechanisms of Bixin on carbon tetrachloride (CCl4)-induced kidney inflammation, fibrosis and oxidative stress in mice. Our results showed that Bixin improved renal damage by decreasing the serum levels of creatinine, urea, uric acid and alleviating kidney fibrosis. Bixin ameliorated CCl4-induced inflammation in kidneys by reducing the levels of TNF-α and IL-1β. Bixin suppressed oxidative stress by decreasing the MDA level and increasing the activation of SOD, CAT and GPx. Furthermore, Bixin increased the levels of PPAR-γ, NQO1, HO-1 and the nuclear translocation of Nrf2 in the kidneys of mice. Bixin supplementation inhibited the activation of TLR4, MyD88, NF-κB, TGF-β and Smad3. Thus, this study demonstrated that Bixin possesses anti-oxidant, anti-inflammatory and anti-fibrosis properties through regulating the Nrf2/TLR4/MyD88 and PPAR-γ/TGF-β1/Smad3 pathways. | | J Anim Sci . 2016 Jan;94(1):125-34. | | Bixin uptake and antioxidative effect and role in immunoregulation in domestic cats[Pubmed: 26812319] | | Bixin, a carotenoid found in the seed of the Annatto plant, , is a potent antioxidant. Carotenoids are readily absorbed from the diet; therefore, the purpose of this study was to examine uptake of Bixin by plasma, lipoproteins, and leukocytes after dietary supplementation in domestic cats and to assess effects on immune response. Female domestic short hair cats (3 yr old; 4.79 ± 0.13 kg BW) were fed a single dose of 0, 1, 5, or 10 mg Bixin, and blood was taken at 0, 1, 2, 4 and 8 h after administration ( = 6/treatment) to determine acute absorption rate. Then, Bixin was fed daily for 14 d to examine steady-state plasma concentrations and subcellular distribution. Following these preliminary experiments, cats ( = 8/treatment) were fed diets containing 0, 1, 5, or 10 mg Bixin/d for 16 wk and blood was collected on wk 0, 6, 12, and 16 for analysis of leukocyte subpopulations, cell-mediated responsiveness, and inflammatory and oxidative biomarkers. Maximal uptake in plasma occurred 1 h after a single oral dose of Bixin, with a maximal concentration of 0.119 μ and elimination half-life of 1.8 to 2.2 h. Daily feeding of Bixin showed a steady-state plasma concentration of 0.110 μ at the greatest doses. Bixin was primarily associated with the high-density lipoprotein fraction of blood lipoproteins and was primarily distributed in mitochondrial fractions (58-59%) of but also in microsomal and nuclear fractions (37-44%). Leukocyte subpopulations in blood were variably affected by dietary Bixin, with an increase ( < 0.05) in total T cells but a concurrent decrease ( < 0.05) in CD18+ and B cell subpopulations. However, plasma IgG increased ( < 0.05) in the 10-mg treatment group by wk 6. Lymphoproliferation was stimulated ( < 0.05) in the 5-mg Bixin treatment group by wk 16, and delayed-type hypersensitivity response increased after nonspecific antigenic challenge. Conversely, when a specific challenge of vaccine was assessed on wk 12 and 16, responsiveness decreased ( < 0.05) in the 10-mg Bixin treatment group. Bixin supplementation surprisingly caused an increase ( < 0.05) in α-acid glycoprotein but had no effect on natural killer cell activity, other subpopulations of leukocytes, or 8-oxo-2›-deoxyguanosine, a DNA damage biomarker. This experiment demonstrated dose-dependent uptake of Bixin in plasma and blood lipoproteins and distribution in leukocyte subcellular components and an impacted immune response through cell-mediated and humoral actions. |
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